| 摘要 |
PURPOSE:To make it possible to judge the inherent pattern of paper and defects by alternately storing the data into pattern memories for every paper when a plurality of the inherent patterns of the paper are contained in one scanning of a self-scanning type photoelectric conversion detector. CONSTITUTION:The image signal of sheet paper 1 undergoes A/D conversion 7. The signal is added into a judging circuit 6 and a comparing circuit 9. The circuit 8 detects the defect having a large contrast. In the circuit 9, a certain value is set so as to detect the defect such as the inherent pattern of the paper whose contrast is small. The output of the circuit 9 is counted with a counting circuit 10 which counts the output during one scanning of a one-dimensional self-scanning-type photoelectric conversion detector 4. At the same time, the data in this line are stored in a line memory 11. When the output of the circuit 10 is more than the specified value, the data in the line memory 11 are transferred into pattern memories. A switch circuit 12 is changed at every specified distance of the paper 1, and the data are alternately stored in the pattern memories 13a and 13b. At every time the circuit 12 is switched, counting is performed with a similarity judging circuit 14 for the memories 13a and 13b. When the result of the counting is the specified value or more, the defective paper is judged. |
